Piston-ring



UNITED STATES LOUIS .A. SAFFORD, OF ST. LOUIS, MISSOURI.

PTsroN-RING.

Specification of Letters Patent.

Patented Sept. 27, 1921.

Application filed. September 8, 1919. Serial No. 322,345. 7

T 0 all whom it may concern:

Be it known that I, LOUIS A. SAFFORD, a citizen of the United States, residing at St. Louis, State of Missouri, have invented certain new and useful Improvements in Piston-Rings, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

The present invention is directed to improvements in piston-rings for use in cylinders of internal combustion engines, and particularly to the closed joint type of split ring, the improved ring being distinguished from both the step joint and the miter joint varieties of ring by reason of the plurality of lapped surfaces disposed across the ring when the ring is contracted to working size or the size it assumes in the'cylinder in which it is intended to operate. In the type of engine referred to (internal combustion) where the piston is driven from one end of the cylinder by highly heated gases having great expansive force, it is eminently desirable to have a one-piece piston-ring which will offer to these gases a maximum impediment to their passage past the ring with successive explosions'on the drive strokes. or on the compression. strokes before explosion; and in order to prevent the gases from flowing past the ring it is 'necessaryto employ a ring with a joint which shall serve as an eifec'tive barrier against such flow. To provide a joint which will effectively and to the necessary degree arrest'the fiowof the gases past the ring is the main objectof the invention; a further object being to provide a ring which may be manufactured at reasonable cost, and one possessing further and other advantages better apparent fromthe following detailed description in connection with the accompanying drawings in which Figure 1 represents a middle longitudinal section of a gas engine cylinder with the piston in elevation showing the improved ring appliedthereto; Fig. 2 is an outer face view of the piston ring whenffree or eX- panded; Fig. 3 is an outer face view of the ring when contracted or compressed to.

working size; Fig. 4 is an enlarged end view of one of the terminals of the ring; Fig. 5 is an enlarged'end view of the opposite terminal; Fig. 6 is an enlarged outer face view of a portion of the ring showing the lap joints formed by compressing the ring to working size; Fig. 7 is a side view of one-half of the piston ring when in the free state; Fig. 8 is a side view of one-half of the ring. when compressed to working slze; Fig. 9 is an enlarged outer face view of a portion of a ring in the free state showmg a modified construction of terminals; Fig. 10 is an end view of one of the terminals of the ring shown in Fig. 9; Fig. 11 is an end view of the opposite terminal of the ring shown in Fig. 9; Fig. 12 is an outer face view of a portion of a ring compressed to working size showing an angle of inclination for the oblique lap-joint of substantially thirty (30) degrees; Fig. 13 is a similar View showing an oblique lap joint inclined at an angle of less than thirty (30) degrees; and Fig. 14 is a similar but enlarged view of a ring slightly compressed showing further modifications of terminals and joints resulting therefrom. I

Refering to the drawings, and for the present to Figs. 1 to 8 inclusive, C represents the engine cylinder, and-P the piston which, in the present example, is shown equipped with two of the improved piston rings. The ring comprises a resilient outwardly springing split metal band 1 having axially parallel inner and outer faces, and of substantially rectangular cross-section, theends of the band being normally dis engaged or separated when the band is free or in the open (Figs. 2, 7 As well understood in the art, the band is received by a peripheral groove it formed in the piston (Fig. 1.) Each end of the band terminates in a tongue t flush with one side of the band and of the thickness of the band, and in a recess or depression 0? offset from the opposite side of the band and of substantially the same dimensions as the tongue, the tongue of one terminal being on the same side of the band as the recess of the opposite terminal, whereby with a compression of the band to working size the tongue is received by said recess as clearly apparent from Figs.

3, 6 and 8 of the drawings. The thickness of V ample being substantially forty-five (45) degrees. When the ring is compressed to working size, the inclined and parallel faces 6 form between them an inclined or diagonal lap joint a, the ends whereof communicate with the parallel lap joints a a, formed respectively by the overlapping of the opposing faces of the tongues t and bottoms of the recesses d, the outer ends of the joints at having leading therefrom the parallel butt joints a, a, formed by the offsets n and the free ends of thetongues t, the joints a opening through the sides of the piston ring. There thus results a compound zig-zag or Z shaped joint comprising the individual joints a", a, a, a, a, the lap joints a, a, being parallel and disposed in planes transverse and at right angles to the axis of the ring, and the butt oints a, a, being parallel and preferably (though not necessarily) parallel to said axis, the lap joint as being at w an incline to the axis of the ring and oblique to the sides of the ring as shown. The joints offering the most effective resistance to the passage of the gases past the piston ring are the parallel lap joints a, a, between the tongues t and bottoms of the recesses d, the gases obviously meeting with considerably less resistance in their passage through the joints a, a", the ring never being completely closed when compressed to woqrlring size (Figs. 3, 6,.) so that while thewalls or faces forming the joints a, a, are in contact, the walls forming the joints a, a, are somewhat separated. In the ordinary step-joint and miter joint rings we have but a single lap joint to arrest the flow of the gases. In my invention we have a plurality of lapjoints (a, a,) parallel to the sides of the ring, with the surfaces forming the joints in permanent engagement so that the improved ring serves as an effective barrier to the passage of the gases, thereby improving the efiiciency of the engine.

In the form of ring above described the engaging faces forming the lap joints a, a, are disposed substantially parallel to. the sides of the ring, that is to say, in planes at right angles to the axis of the ring. I do not however wish to be understood as limiting the invention in that regard, and in Figs. 9, 10 and 11, I show aring 1 with these engaging faces disposed at an incline to the sides ofthe ring and hence at an angle (other than a right angle) to the axis of the ring. The resulting tongues 25 in that event will be thicker on one sidethan on the other, the depths of the recesses d being correspondingly affected. Again,-while in the main form. the angles made by the face a with the inner face of the tongue t and the bottom of the recess d are substantially forty-five 15) degrees, I do not wish to be restricted to this particular angle or to the degree of inclination of the joint a result ng therefrom. Thus, in Fig. 12 is shown a form in which the angle 71 is substantially thirty (30) degrees, and in Fig. 13 we have an angle 2'" less than thirty (30) degrees. Again, while in the forms thus far described the angles are shown shar they may be rounded as shown at m in *ig. 14. In this figure it will also be observed that the free end of the tongue t is substantially in alinement with the offset a" forming the terminal wall of the recess (5 on the same end of the ring, whereas in all the preceding forms it is the base ofthe tongue that is in alinement with the offset forming the terminal wall of said recess. In other words, in the forms shown in Figs. 1 to 13 inclusive the tongues and their cooperating recesses are relatively longer than are the corresponding parts in Fig; 14', the farthest projecting formation in the last modification being the rounded corner formed at the outer end of the bottom wall of the recess d with the inclined face leading therefrom to the base of the tongue t".

Obviously, the details may be changed in other particulars not herein mentioned without in any wise involving a departure from the nature or spirit of the invention. .For example, in each of the several forms described and shown there is but one diagonal joint, and two parallel lap joints (such as a, a,) disposed parallel to the sides of the ring and transverse to the axis of the ring. It is obvious however that a greater or different number of these joints or their equivalents would not necessarily involve a departure from the invention, the basic principle of which is the construction of a ring with a plurality of lap joints substantially parallel to the sides of the ring and transverse to the axis thereof, said joints being connected by diagonal joints inclined to the sides of the ring. j

Having described my invention what .I claim is:

1. A one-piece piston ring comprising a resilient split metal band terminating at each end in a tongue flush with one side of the band, and in a recess offset from the opposite side, the tongue of one terminal being on the same side as the recessof the opposite terminal and adapted to be received by the recess upon compression of the band to working size, the engaging surfaces of said tongues and recesses being at an angle to the plane of the ring, and suitable formations intermediate the recesses and tongues cooperating to form a lap-joint between the bases of thetongues when received by the recesses, said lap-joint being disposed on a diagonal to the sides of the band.

. 2. A resilient splitmetal piston ring comprising a band terminating in formations operating upon compression of the band to working size, to form it Pmlality Of 1 P- joints substantially parallel to the sides of base of the tongue being in alinement with the band, the enga 'ng surfaces of said the terminal wall or offset of the recess in a joints being incline to the plane of the direction across the Width of the ring.

ring, and diagonal lap-joints connecting the I In testimony whereof I aflix my signature 5 first named joints. 1 in presence of two witnesses.

3. A resilient one-piece spit piston rin v terminating at each end in a tongue flusfi LOUIS. R

with one side of the ring, said tongue being I Witnesses: thicker on one side than on the other, and EMIL STAREK, 10 in a recess offset from the opposite side, the Jos. A. MICHEL. 

